1. Field of the Invention
The present invention relates to a structure of touch display panel and, more particularly, to an in-cell touch display panel structure.
2. Description of Related Art
A conventional touch display panel includes a touch panel and a display unit overlapped with the touch panel. The touch panel is configured as an operation interface. The touch panel is transparent so that an image generated by the display unit can be viewed directly by a user without being sheltered by the touch panel. Such well known skill of the touch panel may increase additional weight and thickness of the touch display panel, and may further reduce the light penetration rate of the touch display panel.
On-cell and in-cell touch technology were invented to overcome the drawbacks of traditional touch technology described above. The on-cell technology is to dispose a sensor on the back side of a color filter substrate to form a completed color filter substrate. One of the on-cell touch technologies is provided to dispose a touch sensor on a thin film and then bond the thin film onto the upper one of the two substrates.
The in-cell technology is to dispose the sensor within the LCD cell structure. Currently, there are resistive, capacitive and optical three primary in-cell touch technologies, wherein the resistive touch technology employs two conductive substrates and the voltage variation of a common layer between the two substrates for determining a touch position on the touch display panel.
The in-cell touch technology is provided to integrate the touch sensor within the display unit so that the display unit is provided with the ability of the touch panel. Therefore, the touch display panel does not need to be bonded with an additional touch panel so as to simplify the assembly procedure. Such skill is generally developed by TFT LCD manufactures.
There is older touch control technology known as out-cell, which is typically applied to the resistive and capacitive touch panels. The out-cell touch technology is provided to add a touch module onto a display module. The touch module and the display module can be manufactured by the two separated parties.
However, for all the in-cell, on-cell and out-cell touch technologies, they all need a sensing layer to be configured on an upper or lower glass substrate, which not only increases the manufacturing cost but also complicates the manufacturing process. Therefore, it desired for the aforementioned touch display panel structure to be improved.